I am a seafarer from India and have a C1/D US visa. I am now on vacation in India. Can I transit through a US airport on my C1/D visa for a personal visit to a final destination of Canada? I am not joining or leaving any ship, I just want to transit the USA to my final destination, Canada.
Yes, your visa is valid for transit through the United States for a personal trip unless it bears an annotation stating otherwise.
A C1/D visa is a combo C1 and D visa. C1 Status lets you stay in the US for 29 days on your way to a third country - as such you can use it for your purpose.